Panicum domestication and early sedentism in Northeast China

For the past decade the Xinglongwa culture of eastern Inner Mongolia (Liao River valley) has been regarded as a likely cultural context for the domestication of common millet (Panicum miliaceum), on the basis of significant quantities of Panicum grains associated with some of the many houses excavated at the site of Xinglonggou (see, e.g. Zhao 2011). Recently, new excavations by a Chinese-Israeli collaborative team (with some London archaeobotanists) explored parts of two new small settlement sites of this period, Jiajiagou (5950-5700 BC) and Tachiyingzi (5550-5450 BC), including intensive flotation, have been published this week in PLOSone. At both sites a single dwelling was excavated and sampled, and the archaeobotanical data indicate a predominance of wild plant foods, including walnuts, apricot endocarps, hawthorns, Phellodendron, but Panicum miliaceum is also present is small quantities-- 16 in total at both sites, with more and higher ubiquity at the later site. Most of these Panicum grains are more elongate then plump, with size and L/W ratios that correspond better to Panicum miliaeceum subsp. ruderale, known today as a weedy species but probably descended from, or at least comparable to the origins wild progenitors. We take this to suggest that grain size/shape was still under going evolution over the course of the 6th millennium BC, and thus it may not have been finished evolving into its domesticated form. This fits the now recurrent pattern of protracted domestication processes in cereals (explored previously when "de-centering the fertile crescent", and demonstrated more statistically in Allaby et al "Geographic mosaics and changing rates of cereal domestication").

These data, along with those from Xinglonggou indicate that while Neolithic sedentism had been established in Northeast China by the early 6th Millennium BC, the evolution of domesticated Panicum miliaceum and the establishment of agricultural economies still took rather longer. Another conclusion of the paper is that sedentism and this domestication process took place during stable and quite conducive climatic conditions. This argues against the hypothesis that domestication in this case was driven by climatic stress, or that it should be linked to major climatic fluctuations that characterize the start of the Holocene (a hypothesis promoted by Bar-Yosef 2011, amongst others)

It is worth noting that the later site (Tachiyingzi) also has the presence of a few Setaria italica and S. viridis, and a couple more plump grains (pictured above). While none of these grains was directly dated there is some possibility that more fully domesticated grains will prove to be intrusive. Amongst the direct AMS dates, on wild foods, four proved to be 6th Millennium BC, but one date on fragments from lotus seeds turned out to be intrusive and late Bronze Age. This highlights the need for more direct dating of crop remains, a point highlighted by recent debates over the arrival of wheat in Late Longshan China, for which numerous false alarms have been dismissed via direct radiocarbon dating (see "Assessing the occurrence and status of wheat in late Neolithic central China: the importance of direct AMS radiocarbon dates from Xiazhai").      

So the case for a millet domestication in Northeast China in strengthened. This does not rule out other dometciation centres-- which there must have been for Setaria italica at least, and perhaps Panicum milieceum. Domestication can be regarded as taking place alongside and after the emergence of sedentism, but further data are needed to better document this, and to assess the extent to which initial cultivation  of wild millet was linked to the shift to sedentism or not. 

The eastern fertile crescent returns

The recent paper in Science by Riehl et al. on  the evidence for Chogah Golan has rightly garnerd wide attention (e.g. Science news; commentary by Willcox). This is a highly significant paper, which shows that the beginnings of cultivation were indeed mutlicentric within the fertile ccrescent, and it suggests that there was an independent domestication process for emmer wheat in the eastern fertile crescent in addition to that in the western fertile crescent. 

Are there surprises? Yes. The big surprise here is the emmer wheat domestication, as many have argued on biogeographical and modern genetic grounds that there should have been and eastern and western barley domestication, but this has been little considered for wheat. This is mainly because the modern distribution of wild wheats does not extend that far east and south, and thus the data from the Chogha Golan, especially the lower levels indicates that the distribution of wild wheats at the start of the Holocene/end of the Pleistocene was indeed different and more extensive than modern wild wheats. This further implies that some starts to cultivation and domestication events could have drawn on wild population that are extirpated today and therefore are not reflected in modern wild germplasm collections. Modern collection used in genetic studies are only a fragmentary representation of the past, although geneticists often fall into the trap of assuming that good wild sampling in the modern day means they have captured the wild diversity from which domestication began.

What this what we/ I suspected? Yes. I am one of a number of scholars who have been arguing for a multicentric process of parallel starts to cultivation and parallel, and protracted, domestication processes around the Fertile Crescent, i.e. De-centering the Fertile Crescent. Mostly we have argued this on contrasts between the Southwest and the north/central fertile crescent and the contrasts between morphological diversity in archaeological samples and that in modern germplasm. As the authors here note with their triticoids, they are dealing with a wild wheat type not well represented in modern collections; this is equally true of early domesticated wheats in Syria/Anatolia and even in Neolithic Europe. In the Neolithic there are extinct genetic lineages, that are morphologically distinct, that are not found in modern landraces. In other words there are several lost crops of early agriculture. 

Were things really synchronous? This remains a little unclear. The lower levels seems to have pre-domestication cultivation of barley and lentil and lost wild wheat in the equivalent of PPNA/ EPPNB time periods-- this is indeed the same period that we see this in Jordan, Israel, north and south Syria. However in the Chogha Golan there is then a break and a large minority of domesticated type emmer appears. But this is mainly in the Late PPNB (ca. 7800 BC)! By this period domesticated crops are well established at higher frequencies (usually 60-70% non-shattering spikelet bases) in western fertile crescent assemblages (mainly of einkorn wheat or barley). Emmer at Tell Aswad in Syria is ~23% non-shattering at 8300 BC and at Tell el-Kherkh in NW Syria it is 44% at ca. 8400 BC. This evolution of non-shattering (a key domestication trait) appears  slightly ahead in the west. This could mean the that 25%-domesticated assemblage at upper Chogha Golan has spread from early cultivated population elsewhere that were undergoing the gradual selection for non-shattering, or it could indicate a local process, maybe not at Chogha Golan, but nearby that simply got started a bit later. 

I would note in passing, that there was one previous suggestion of eastern emmer domestication, many years ago by Hans Helbaek in the 1960s based on rather poor samples collected by the Braidwood expedition at Jarmo in Iraqi Kurdistan in the 1950s, in which Helbaek reported intermediate types and mixtures of wild and domesticated emmer. These data were never quantified nor fully published but would potentially fit with the Chogha Golan finds. So a return to Jarmo may yet have some important archaeobotanical contributions to make.

On the whole, however, these new data offer strong support from a new dataset and a different research group for what I have been championing as a paradigm shift in agricultural origins research. From the paradigm of a rapid and singular agricultural revolution to a paradigm of protraction and entanglement that was messy and non-centric. (See, e.g. refs 2 and 19 cited by Riehl). 

De-centering the fertile crescent

The Near Eastern "fertile crescent" is the classic centre of origin for domesticated plants. Although when James Breasted coined the term (1906) he was thinking about the beginnings of agrarian civilizations in Egypt and Mesopotamia. The term become subsequently linked to Gordon Childe's notion (1935) of the "Neolithic Revolution" and with Vavilov's "centres of origin" idea, and the Fertile Crescent became, in archaeological argot, the centre of agricultural origins par excellence. In another classic paradigm-setting paper Jack Harlan used the Fertile Crescent as representative of a "centre" of origin, a focused area in which a package of crops was domesticated together, opposed to his notion of a "non-centre" of diffuse origins of crops that were not-packaged and spread out in domestications in space and time, of which the sub-Saharan savannah was perhaps the classic Harlanian exemplar. Within "centres" the Neolithic was meant to be a revolution, domestication rapid, and hunter-gatherers transformed to village farmers in one process. However, the evidence for this has been gradually unravelling for the Near East, with domestication-- the evolution of domestication syndrome traits in crops-- taking place quite slowly (3000-4000 years), and taking place not in a focused area, as a package of crops, but spread out and with as many dead-end proto-domesticates as paths into the crops and farming systems we know for later prehistory or history. In other words, there was no Neolithic Revolution as such but evolutionary processes, in the slow Darwinian sense, in which many incremental changes and transformations only added up to something revolutionary in retrospect, after millennia (some 150 to 200 human generations) of small steps.

You can find the case for this made in the December World Archaeology in my joint paper with George Willcox and Robin Allaby "Cultivation and domestication had multiple origins: arguments against the core area hypothesis for the origins  of agriculture in the Near East" which is a companion piece with our in press paper in the Journal of Experimental Botany  "Early agricultural pathways: moving outside the ‘core area’ hypothesis in Southwest Asia". Both are responses precipitated by publication late last year by Abbo et al. of a re-iteration of the "core area" view of  a tightly focused area where a single package of "founder crops" was domesticated rapidly. Such a view requires the assumption that archaeobotanical evidence is false fossil record, a poor reflection of actual domestication processes, i.e. that the gradual changes that appear in systematic archaeobotanical evidence, are somehow misleading or mistaken. I find this hard to accept-- perhaps because I am a practicing archaeobotanist and regard the preserved grains and rachises of prehistoric crops as our most material record of what these plants were like and how they were used in the past-- but also because recent years have seen increasing sampling and sample size and it is the increase in these data, and the detail with which they have been studied, that most points to the more gradual evolutionary processes. In addition, the "core area" view delimits a smaller number of founder crops and sets aside (or even rejects implicitly) the presence of past cultivars and domesticates now extinct, from the Abu Hureyra rye, 2-grained einkorn, the "new type" emmer ('striate emmeroid'), or the Gilgal oats-- all species which are the product of careful efforts of archaeobotanists to document the material remains of past crops and not to assume that all crops that ever were must still exist today. These constitute the "lost crops" of the Fertile Crescent just as much as Iva annua is a lost crop of the American midwest.  Coupled with the genetics of known crops that support multiple "domestication pathways" (such as in barley, emmer, pea, probably one-grained einkorn), the Fertile Crescent as a whole was host to something like 20 domestication "events," only a fraction of which can be localized in any one sub-area of the Fertile Crescent or can be expected to be present in modern germplasm collections. With this number of domestications and their diffuse nature across the Near East, the Fertile Crescent as a whole starts to look like a Harlanian "non-centre". On the level of individual crops and domestication events there may well be many centres of origins but in terms of regions it look increasingly like all were non-centres. The closer one looks for a core centre, the blurrier it becomes. 

Last year I declared in General Anthropology, a paradigm shift in agricultural origins research. Perhaps rather pretentious, but it remains the case that domestication appears to be a slower process as we gather more evidence, and there is evidence for more places of domestication around the world (North America, South India, separate North and South China, various parts of Africa, New Guinea, to name a few). This year I have put my money where my mouth is, and brought out a number of contributions looking at domestication processes in the Near East in particular and in comparison to the best documented crops from elsewhere (mainly in the Old World). This includes attempting to objectively calculate rates of domestication in terms of phenotypic units, the darwin and haldane, reported in terms of more general conclusions-- that domestication was slow and not somehow special compared to other forms of evolution-- in the journal Evolution (Purugganan and Fuller), and unpacked with more consideration of the variation across crops in the Near East and elsewhere in Vegetation History and Archaeobotany (Fuller, Asouti, Purugganan). See also the updated rachis data of Tanno and Willcox (2011)phenotypic change may differ in adjacent geographical contexts, and in particular that there appear to be in island effects on Cyprus, where grain size change was sped up (Lucas, Colledge, Simmons & Fuller). A careful consideration of the hard evidence, such as the essay assaying the southern Levant (Asouti & Fuller), shows that even for the Fertile Crescent we still lack the evidence we need to be clear about domestication processes in particular micro-regions, early cultivation or when agriculture emerged (keeping in mind that cultivation, domestication and agriculture are really different things from among the many transitions that gradually came together). We also note that there is alot more work to be done on the species that were important wild food stuffs, which were abandoned as cereal agriculture took off, the small-seeded grasses and legumes, wild nuts and nutlets-- evidence in other new archaeobotanical datasets such as that from Jordan (el-Hemmeh) of White et al. (which reports important evidence for how barley was harvested prior to domestication) or 3 sites from the northern and eastern Fertile Crescent (SE Turkey and Iran) of Riehl et al.. Of course as the role of many wild foods along side pre-domesticated cereals gains recognition, the difficulty of being clear what was a likely weed as opposed to gathered become acute-- an issue discussed in a short paper by Willcox on early weeds. Another recent paper out of London (Wollstonecroft, Hroudova, Hillman & Fuller on Bolboschoenus) illustrates an example of challenges that still confront archaeobotanical identification, and the the potential ecological and dietary implications of refining these to species level, in this case for the sedge Bolboschoenus glaucus.

 Most of these papers, now available on-line for a forthcoming Vegetation History and Archaeobotany issue on the Near East which will illustrate the revised (and more diverse) understanding of the precursors of Fertile Crescent agriculture: the tides seem to have turned on the simpler core area paradigm!

Parallel origins: true modern human lithics in India (as true for agriculture)

The latest publication from the Petraglia & Korisettar palaeolithic research team, working in South India, was published last week in PNAS—Population increase and environmental deterioration correspond with microlithic innovations in South Asia ca. 35,000 years ago. This study dovetails nicely with recent simulation modelling effort of some UCL colleagues (Adam Powell, Mark Thomas, and Stephen Shennan, director of the Institute of Archaeology), published in Science last month. (The appearance of these two papers close together is entirely coincidental). This simulations suggest that behavioural innovations, such as modern human behaviour, should be expected to emerge when circumstances are right (especially due to demographic factors of higher interactoing populations), and to be maintained only if demographic circumstances permit (and therefore disappear if populations decline).

These two studies together represent importance counters of an orthodoxy that sees ‘modern’ behaviour as emerging once, and therefore being a great invention when hard cognitive architecture came into place, perhaps even driven by a key genetic mutation for intelligence. Such is the orthodoxy implied by classic textbooks on human evolution, such as by Richard Klein (at least as was used when I was a student) or the recent reviews by Paul Mellars (e.g. his Science paper of 2006). In this view modern humans, heir cognitive abilities and the behavioural application of those abilities emerged once (in Africa) and spread out of Africa (once) to bring intelligent modern everywhere else (perhaps at sometime between 60,000 and 40,000—depending on whether one prefers to emphasize the earliest possible dates for Australia or the Upper Palaeolithic transition in Europe). The evidence from South Asia shows clearly that toolkits were middle Palaeolithic (and in this sense not ‘modern’) from >75,000 to 35,000 years ago, and yet genetics suggests that these would have been anatomically modern humans (and they must have moved through South Asia earlier than their arrival in Australia sometime between 60,000 and 50,000). The bottom line is there is a good evidential case to be made, congruent with the modelling of Powell et al., that the cognitive architecture for modern behaviour was around but the innovations that we regard as ‘modern’ emerged when social and environmental circumstances demanded.

There is a parallel here to where thinking on agricultural origins is moving. There has long been an orthodoxy that agriculture was a great and rare invention, and that agriculture came to most regions by the migration of farmers from a few centres of the influence of a good idea. In the more extreme cases, only 3 centres of origin (Mexico, Near East and China) are accepted. But the evidence of archaeobotany—where it is available—combined with the biography of wild progenitors, and where avail able the genetics of crops/livestock, suggest that there was many more centres in which societies converged on agriculture—the behavioural changes towards manipulation of the environment in favour of the reproduction of a few food species (domestication, the genetic sense, was an unintended consequence of these behavioural shifts, when the genetics of the species allowed). In my most recent attempt to sift through the combined data, I concluded that there is strong case for 24 separate instances of agricultural origins globally—although as many of these are poorly documented and geographically close together one might reduce this to 13, as per the map below from Purugganan & Fuller:

The point is that agriculture, like modern human behaviour, was not a one time great invention, but the product of social and environmental circumstances to which human groups with the same cognitive potential responded in parallel ways. The question in both cases is: what were the common denominators of those circumstances?